A percutaneous heart valve implantation (PHV) has been developed by Edwards Lifesciences PVT Ltd. and is described in U.S. Pat. No. 6,730,118, which is herein incorporated by reference in its entirety. A primary concept behind using a PHV is implantation inside the stenotic region of a calcified native valve without removing the native valve. The PHV stents the stenotic valve open and uses it as an attachment means for the PHV.
A major design parameter of the PHV is the folded or crimped profile. The crimped profile directly influences the ability to insert the PHV into the femoral artery or vein. Accordingly, a smaller profile allows for treatment of a wider population of patients, with enhanced safety.
Generally, the primary attachment mechanism of the PHV to the native valve is friction. This friction is generated by radial contact forces between the stenotic valve and the metallic frame of the PHV. A proper sizing should provide for secure attachment of the PHV to the native valve and provide good sealing to avoid, for example, paravalvular leaks.
Prior PHV implantation methods and apparatus include Schreck in U.S. Pat. No. 6,454,799, entitled, “MINIMALLY-INVASIVE HEART VALVES AND METHODS OF USE”, which describes expandable heart valves for minimally invasive valve replacement surgeries. In a first embodiment, an expandable pre-assembled heart valve includes a plastically-expandable annular base having a plurality of upstanding commissure posts. A tubular flexible member including a prosthetic section and a fabric section is provided, with the prosthetic section being connected to the commissure posts and defining leaflets therebetween, and the fabric section being attached to the annular base. In a second embodiment, an expandable heart valve includes an annular tissue-engaging base and a subassembly having an elastic wireform and a plurality of leaflets connected thereto. The annular base and subassembly are separately stored and connected just prior to delivery to the host annulus. The leaflet subassembly is stored in its relaxed configuration to avoid deformation of the leaflets. The expandable heart valves can be implanted using a balloon catheter. The leaflets of the heart valves are secured to the commissure regions of the expandable stents using a clamping arrangement to reduce stress.
Spenser et al. in U.S. patent application No. 20030153974, entitled “IMPLANTABLE PROSTHETIC VALVE”, describes a prosthesis device suitable for implantation in body ducts. The device has a support stent that is adapted to be initially crimped in a narrow configuration suitable for catheterization through a body duct to a target location and adapted to be deployed by exerting substantially radial forces from within by means of a deployment device. The support stent includes a plurality of longitudinally rigid support beams of fixed length, and a valve assembly comprising a flexible conduit having an inlet and an outlet made of pliant material attached to the support beams to provide collapsible slack portions of the conduit at the outlet. When flow is allowed to pass through the valve prosthesis device from the inlet to the outlet, the valve assembly is kept in an open position, whereas a reverse flow is prevented due to the collapsible slack portions of the valve assembly that collapse inwardly to block the reverse flow.
Another known technique for implanting a prosthetic valve is a transapical approach where a small incision is made in the chest wall of a patient and the catheter is advanced through the apex (i.e., bottom tip) of the heart. Transapical techniques are disclosed in U.S. Patent Application Publication No. 20070112422, which is hereby incorporated by reference. Like the transvascular approach, the transapical approach includes a balloon catheter having a steering mechanism for delivering a balloon-expandable prosthetic heart valve through an introducer to the aortic annulus. The balloon catheter includes a deflecting segment just proximal to the distal balloon to facilitate positioning of the prosthetic heart valve in the proper orientation within the aortic annulus.
Yet another known technique for implantation of a prosthetic in the aortic valve is through the use of a two-balloon catheter. For example, such a system is shown in U.S. Pat. No. 6,908,481, entitled “VALUE PROSTHESIS FOR IMPLANTATION IN BODY CHANNELS.” Typically, two balloons are fixed on a catheter shaft and are separated by a few millimeters. The first balloon carries a frame for scaffolding a stenosed orifice after initial dilatation and the second balloon carries an expandable valve. The first balloon is sufficiently strong to avoid bursting even at very high pressure. The second balloon does not need to be as strong as the first and can, therefore, be thinner, occupying less space and being easier to expand with lower pressure. The time interval between expansion of the first and second balloons must be short because there is a total aortic regurgitation back through the frame towards the left ventricle. Such a regurgitation is a hemodynamic condition that cannot be maintained for more than a few seconds.
In order to decrease the possibility of aortic regurgitation, U.S. Pat. No. 6,425,916, entitled “METHODS AND DEVICES FOR IMPLANTING CARDIAC VALVES” introduces a temporary valve. However, the temporary valve must be removed after the permanent valve is deployed, which requires an additional surgical step and potential complication.